Ryōgoku Kajinosuke IV (born 30 July 1962 as Hideaki Kobayashi) is a former sumo wrestler from Nagasaki, Japan.
After taking part in two playoffs for the jūryō championship in November 1986 and January 1987 he was promoted to the top makuuchi division for the March 1987 tournament.
Until this point he had been fighting simply as Kobayashiyama, based on his own surname, but to mark his promotion he was granted the shikona of Ryōgoku, which had previously been used by three previous wrestlers from his Dewanoumi stable, most notably sekiwake Ryōgoku Kajinosuke II, who won the makuuchi division yūshō in 1914 at his first attempt.
Injury problems in his later career forced Ryōgoku's demotion back down to jūryō a couple of times, and he retired in January 1993.
Sanshō key: F=Fighting spirit; O=Outstanding performance; T=Technique Also shown: ★=Kinboshi; P=Playoff(s) Divisions: Makuuchi — Jūryō — Makushita — Sandanme — Jonidan — Jonokuchi